Purpose of Hydraulic Filters

All hydraulic systems have a common need for protection
from harmful contaminants. Hydraulic filters help minimize maintenance costs through good contamination control. In systems utilizing a full-flow filter, all of the oil is filtered each complete circulation cycle. Every full-flow filter must be protected by a bypass valve. The valve may be located in the filter, the filter mounting base or in a line connected to the inlet and outlet of the filter assembly. A full-flow filter mounted in the return line permits cleaning of the fluid before it returns to the reservoir. In this arrangement, the filter must be able to withstand the maximum pressures generated by the pump.

Types of Contaminants

There are many kinds of contaminants found in hydraulic systems, but they can be divided into two types, chip and silt. Chips are large particles which can cause sudden and
catastrophic failures such as the sticking of a valve or the binding or jamming of a pump or motor. Silt consists of very fine dirt particles which are often invisible to the naked eye. Failures due to silt occur over a period of time because they slowly eat away the internal components. Good system maintenance and proper filtration are the prerequisites to long life for hydraulic systems. Contamination affects hydraulic systems in many ways. Acids forming due to fluid breakdown and mixing of incompatible fluids in the system cause corrosion. Contaminants can cause increased internal leakage which lowers the efficiency of pumps, motors and cylinders. Internal leakage decreases the ability of valves to control flow and pressure accurately. It also wastes horsepower and generates excess heat. Sludge or silting can cause parts to stick or seize. All of these things can be prevented with good filtration.

Servicing Hydraulic Filters

Proper hydraulic system maintenance procedures can be summed up in one word, cleanliness. Good clean procedures should be used in any filter system but particularly in hydraulics. The introduction of one chip into the system could result in high maintenance costs and downtime. All exterior components of the filter system should be thoroughly cleaned before disassembly. During disassembly and replacement of the filter and other  components, all parts should be cleaned and inspected
prior to installation of the new filter.

Hydraulic Filters Available From AMSOIL

AMSOIL offers Donaldson heavy-duty high-pressure filters to protect critical hydraulic components such as cylinders, motors and valves. All of Donaldson’s heavyduty hydraulic filters contain synthetic filter media specially developed by Donaldson for high efficiency liquid
filtration. AMSOIL also carries Donaldson DURAMAX®, wellknown as the highest rated spin-on style filters available. DURAMAX filters are available with synthetic or cellulose media and are used most often in return-line positions. Donaldson low-pressure filters are the most commonly used type of filter in hydraulic circuits, usually as return-line filters. AMSOIL carries Donaldson low-pressure filters that offer flow/pressure combinations to fit most applications. The Donaldson P550606 hydraulic filter can also be used in five-speed manual Allison transmissions commonly used in Duramax diesel engines found in Chevy and GMC trucks. The P550606 replaces the Hastings HF992. Other hydraulic filter applications include tractors, backhoes, presses or essentially anywhere there are hydraulic lines.

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